JP2758903B2 - Color electrostatic recording sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrostatic recording sheet, and in particular, to a CA
The present invention relates to a color electrostatic recording sheet suitable for an electrostatic printer / plotter for outputting a color drawing in a D (Computer Aided Design) system.

[Prior Art] An electrostatic recording sheet is formed by sequentially providing a conductive layer and a dielectric layer on at least one surface of a support, and applying a voltage from a recording electrode to the surface of the dielectric layer to form an electrostatic latent image. Then, after developing with a toner (colored powder or liquid developer), the toner is fixed by heat, pressure, drying or the like to obtain a recording.

With the recent development of computers, CAD technology has been developed that allows computers to design drawings of machinery, electrical wiring, buildings, etc., and outputs the results to an electrostatic printer / plotter. Among them, there has been a growing need for sharpening by color display in order to make complicated drawings easy to see.

In particular, in the design of mask patterns such as ICs and LSIs, complicated drawings are created, and there is a strong need for colorization. There is also a need to output the results of data processing by a computer with an electrostatic printer / plotter and display them in color. For example, a color electrostatic printer / plotter is used as a data output for oil exploration and underground resource exploration. In color electrostatic recording, a liquid image of three primary colors (cyan, magenta, and yellow) and a black liquid toner are used, and a process of forming a latent image, developing, and fixing is repeated for each color toner to obtain a color image. Things.

In order to obtain a halftone density, a dither method for adjusting the density of a latent image per unit area is used. For example, 16 dots / m
When recording at a recording density of m, a total of 16 dots, that is, 4 dots in the vertical direction and 4 dots in the horizontal direction, is used as one unit, and a density of 16 gradations can be obtained by changing the number of dots to be recorded therein. . Further, multicolor recording can be performed by mixing two of the three primary colors. For example, green color can be obtained by performing yellow recording on cyan recording, blue violet can be obtained by performing magenta recording on cyan recording, and red can be obtained by performing yellow recording on magenta recording.
An intermediate delicate color tone and density can be expressed by the mixing ratio of these two colors.

Further, four or four color toners including black can be freely combined in two or three colors to reproduce various desired color tones.

[Problems to be Solved by the Invention] However, in the conventional electrostatic recording sheet, when two-color or three-color superimposed recording is performed, the toner attached before is peeled off, and the toner attached later is replaced. You have a problem.

In particular, when performing yellow recording on cyan or magenta recording at a low recording temperature of 10 ° C. or less, there is a problem that a part of the cyan or magenta toner peels off from the dielectric layer and the yellow toner adheres.

An object of the present invention is to provide a color electrostatic recording sheet capable of performing clear high-contrast color recording without causing toner peeling even when recording at a low temperature of 0 ° C. by solving the above problems. It is.

[Means for Solving the Problems] As a result of intensive studies to improve toner peeling, the present inventors have found that toner peeling is likely to occur at a low temperature of 10 ° C or lower, and hardly occurs at 20 to 30 ° C. They found that it was closely related to the glass transition temperature (Tg) of the dielectric layer resin. It is presumed that the reason is that the adhesive force between the dielectric layer resin having a high Tg and the toner particles is low at a low temperature or the toner particles are weak. And Tg
It has been found that when a dielectric layer resin at 20 to 40 ° C. is used, toner separation does not occur even when performing multicolor recording at a low temperature of 0 ° C.

When Tg exceeds 40 ° C., toner peeling occurs at a low temperature of about 0 to 10 ° C., and when Tg exceeds 50 ° C., there is a problem that it occurs even at around normal temperature.

On the other hand, when the Tg is less than 20 ° C., when the electrostatic recording sheet is wound into a roll, the blocking property becomes strong, and the unwinding becomes difficult.

Accordingly, the present invention provides a color electrostatic recording sheet having a conductive layer and a dielectric layer provided on at least one side of a support in this order, wherein the dielectric layer comprises a dielectric layer resin, a white pigment and a fluorescent dye, and the dielectric layer resin comprises Glass transition temperature is 20 ℃ ~ 40
° C, and the mixing ratio of the dielectric layer resin and the white pigment is in the range of 90/10 to 50/50, and 0.3 to 5% of the fluorescent dye is added. And a color electrostatic recording sheet.

When the dielectric layer resin is a single resin composed of one type of monomer, the Tg of the dielectric layer resin is such that the thermal expansion coefficient, isothermal compression rate,
It is expressed as a temperature at which various thermodynamic quantities such as a constant pressure heat capacity change discontinuously with a temperature change. For example, it can be measured as a specific heat measurement by a differential thermal analyzer (DSC) or as an inflection point of a temperature-volume curve by dilatometry.

The Tg of a single resin is, for example, Polymer Data Handbook-
Basic Edition-pages 525 to 541 (edited by The Society of Polymer Science, Japan, Showa 61)
(Published by Baifukan on January 30, 2001), and the most frequently used ones are as follows, but those usable in the present invention are not limited to these. Even if the single resin has a Tg of 40 ° C. or more or less than 20 ° C., it can be used as a copolymerized resin or by mixing two or more resins to adjust the Tg.

When the dielectric layer resin is a copolymer resin composed of two or more types of monomers, Tg represents the glass transition temperature of the resin composed of a single monomer as Tg ₁ , Tg ₂ ... Tg _n , the weight fraction ω ₁ , Assuming that ω ₂ ... ω _n , Tg = ω ₁ Tg ₁ + ω ₂ Tg ₂ +... + ω _n Tg _n ... (1) from Gordon and Taylor's theory.

Further, the glass transition temperature when two or more kinds of single resins or copolymer resins are mixed depends on the compatibility of the mixed system, and in a mixed system having poor compatibility, Tg of each resin may appear separately. Those which can be used as the resin for the dielectric layer have relatively good compatibility, and the Tg may be evaluated according to the formula (1) for convenience.

Polyacrylic acid 103 ° C, Polymethyl acrylate 10 ° C, Polyethyl acrylate -24 ° C, Polypropyl acrylate -37 ° C Polyisopropyl acrylate -6 ° C, Polybutyl acrylate -54 ° C, Polyacrylic acid-sec- Butyl-22 ℃, tert-butyl polyacrylate 43 ℃, 3-pentyl polyacrylate-6 ℃, heptyl polyacrylate-60 ℃, hexyl polyacrylate-57 ℃, 2-ethylhexyl polyacrylate-85% Octyl polyacrylate -65 ° C, hexadecyl polyacrylate -6 ° C, polymethacrylate 228 ° C, polymethyl methacrylate 105 ° C, polyethyl methacrylate 65 ° C, polypropyl methacrylate 35 ° C, polyisopropyl methacrylate 81 ° C , Polybutyl methacrylate 20 ° C, poly-sec-butyl methacrylate 60 ° C, polymethacrylic acid tert-butyl 107 ° C, polyisobutyl methacrylate 53 ° C, polyhexyl methacrylate -5 ° C, polyoctyl methacrylate -25 ° C, polydecyl methacrylate -45 ° C, polyacrylamide 109 ° C, polyvinyl chloride 81 ° C, polychlorinated Vinylidene -18 ° C, polyvinyl acetate 32 ° C, polystyrene 100 ° C, polyethylene terephthalate 69 ° C.

The dielectric layer is mixed with white pigment of inorganic and organic said dielectric layer resin, coating as coating amount after drying the obtained dielectric layer paint on the conductive support is 2.0~7.0g / m ² You can get it. Inorganic and organic white pigments to be mixed with the dielectric layer resin include, for example, calcium carbonate, clay, calcined clay, lithopone, titanium dioxide, zinc oxide, aluminum hydroxide, barium sulfate, silica, magnesium carbonate,
Urea resin beads, acrylic resin beads, ethylene resin beads, acrylic resin beads, ethylene resin beads, propylene resin beads, benzoguanamine resin beads, silicon resin beads, and the like can be used. The mixing ratio between the dielectric layer resin and the white pigment is 90/10 to 50/50. In order to enhance the visual whiteness, a fluorescent dye is added in an amount of about 0.3 to 5% to the dielectric layer paint.

As a coating method, a normal coating method such as a Meyer bar method, a blade method, a reverse roll method, and a gravure roll method can be used.

The support used in the present invention may be a high-quality paper or a roll paper made by a Yankee machine, or a laminate of 3 to 5 layers of a thin film obtained by melt-kneading a polyolefin resin and a white pigment, stretching after forming a film. There is a synthetic paper obtained by doing this. These opaque supports are preferably those having high whiteness in order to enhance the clarity of color recording. In addition, a translucent support such as glassine paper, resin-impregnated paper, or translucent synthetic paper, or a highly transparent film such as a polyethylene terephthalate film, a polycarbonate film, or a polypropylene film can also be used.

The conductive layer provided on the support can be obtained by applying a conductive layer paint composed of only a conductive agent, or a conductive agent and a white pigment to improve the blocking property of the conductive layer due to the hygroscopicity of the conductive agent, and bonding. It can also be obtained by applying a paint containing an agent.

The conductive agent used in the conductive layer paint is a cationic conductive resin, for example, a quaternary ammonium salt such as polyvinylbenzyltrimethylammonium chloride, polydimethyldiallylammonium chloride, styrene acrylate trimethylaminoethyl chloride, and an anionic conductive resin. Metal oxide semiconductors such as aluminum oxide-doped zinc oxide, antimony-doped stannic oxide, metal fine powder, organic or inorganic salts, and interfaces, in addition to polystyrene sulfonate, polyacrylic acid, and polyvinyl phosphonate. A conductive agent such as an activator may be used alone or in combination.

Inorganic and organic white pigments blended in the dielectric layer can be used in the same manner as the white pigment blended in the conductive layer paint. Adhesives to be blended in the conductive layer paint are polyvinyl alcohol, starch, methylcellulose, carboxymethylcellulose,
Use water-soluble resin such as casein, water-soluble acrylic resin, or water-dispersible adhesive such as acrylic emulsion, polyvinyl acetate emulsion, polyvinyl chloride emulsion, polyvinylidene chloride emulsion, SBR latex, MBR latex alone or in combination. be able to.

The conductive layer paint contains a conductive agent in an amount of 30% or more in order to obtain necessary conductivity. In order to improve the blocking property and whiteness of the conductive layer, it is preferable to mix 30 to 50% of a white pigment and 10 to 30% of an adhesive. Also, in order to enhance the visual whiteness, a fluorescent dye can be added to the conductive layer paint in an amount of about 0.3 to 5%.

The conductive layer paint is air knife method, Meyer bar method,
Coating is performed on one surface of the support by a normal coating method such as a blade method, a reverse roll method, or a gravure roll method so that the coated amount after drying is 1 to 15 g / m ² .

In order to improve the recording quality and to prevent curling, it is also effective to apply the coating on the opposite side of the support as necessary.

The obtained conductive support is used by performing a smoothing treatment with a super calender, a gloss calender, a machine calender, etc., as necessary, in order to reduce wrinkles generated during drying and to improve coating properties of the dielectric layer. I do.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples. Parts in the examples represent parts by weight.

Examples 1 and 2, Comparative Examples 1 and ² Cationic conductive agent (Chemistat 5500, solid content 34%, manufactured by Sanyo Chemical Co., Ltd.) 176 parts calcium carbonate on the felt surface (F side) of high-quality paper having a basis weight of 52.3 g / m ² (Pelite # 500, average particle size 1.65μ
m, manufactured by Nitto Powder Co.) 30 parts Vinegar-acrylic emulsion (Movinyl 730, solid content 4)
6 parts, made by Hoechst synthesis 22 parts Fluorescent dye (Kayahole path liquid, solid content 50%, made by Nippon Kayaku) 2 parts 103 parts of water g / m ² to give a conductive layer.

The same paint was applied to the back surface by an air knife method so that the applied amount after drying was 3.0 g / m ² .

The Beck smoothness of the conductive layer surface was set to 500 seconds by the super calendar treatment. Attach a stirrer reflux condenser and a nitrogen inlet tube, and place styrene, 2-ethylhexyl acrylate, azobisisobutyronitrile (AI
BN) is mixed with the composition shown in Table 1 and injected together with toluene under a nitrogen atmosphere.

The mixture is heated to 60 ° C. while passing through nitrogen and stirring slowly, and polymerized for 4 hours. After cooling the polymer solution, the precipitate obtained by dropping into petroleum ether is washed with petroleum ether and dried in a vacuum drier to constant weight.

A dielectric layer paint composed of 7 parts of the obtained styrene-ethyl acrylate 2-ethylhexyl copolymer resin, 3 parts of calcium carbonate (NS-400, average particle diameter of 1.7 μm, manufactured by Nitto Powder Chemical Co., Ltd.) and 30 parts of toluene was prepared. Coating was performed by a Mayer bar method so that the coating amount after drying was 4.0 g / m ² on the treated conductive layer to obtain an electrostatic recording sheet.

Examples 3-4, Comparative Examples 3-4 The procedure of Example 1 was repeated, except that a mixture of methyl methacrylate, butyl acrylate and acrylic acid having the composition shown in Table 1 was used instead of styrene and 2-ethylhexyl acrylate. A copolymer resin was produced in the same manner as in Example 1, and an electrostatic recording sheet was produced.

Example 5 3.5 parts of the copolymer resin prepared in Comparative Example 1 3.5 parts of the copolymer resin prepared in Comparative Example 2 3 parts of calcium carbonate (NS-400) 3 parts Toluene 30 parts of a dielectric layer paint was prepared. It was coated on the used conductive support in the same manner as in Example 1 to obtain an electrostatic recording sheet.

Example 6 An electrostatic recording sheet was produced in the same manner as in Example 5 using the copolymer resins produced in Comparative Examples 3 and 4.

Evaluation of each case Using a Versatech color electrostatic plotter, 25
Color recording was obtained at 45% RH at 45 ° C. and 30% RH at 5 ° C., and the density and super-colored portions (cyan + yellow, magenta +
(Yellow) was evaluated and the results are shown in Table 1.

When the Tg of the dielectric layer resin was 20 to 40 ° C. as in Examples 1 to 6, toner peeling did not occur and recording with good contrast was obtained.

When Tg was 40 ° C. or higher as in Comparative Examples 1 and 3, the toner was peeled off, and the image was unclear.

Further, in Comparative Examples 2 and 4, the Tg was less than 20 ° C. and the film was blocked in a wound state, and when recording was performed, only an unclear recording with strong fog was obtained.

[Effects of the Invention] In the case where heavy-color recording is performed by a color electrostatic plotter according to the present invention, toner separation does not occur even at a low temperature condition of 0 ° C., and a clear color with high contrast can be obtained. An electrostatic recording sheet can be provided.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-98324 (JP, A) JP-A-50-98325 (JP, A) JP-A-50-123431 (JP, A) JP-A-55-98341 9561 (JP, A) JP-A-56-66850 (JP, A) JP-A-1-255860 (JP, A) JP-A-60-211465 (JP, A) JP-A-1-202754 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 5/02 101

Claims (1)

(57) [Claims] 1. A color electrostatic recording sheet comprising a support and a conductive layer and a dielectric layer provided on at least one side of the support in this order, wherein the dielectric layer comprises a dielectric layer resin, a white pigment and a fluorescent dye, and the dielectric layer resin comprises The glass transition temperature is selected from those having a temperature of 20 ° C. to 40 ° C., and the mixing ratio of the dielectric layer resin and the white pigment is in the range of 90/10 to 50/50, and the fluorescent dye is 0.3%. A color electrostatic recording sheet, which is added in an amount of 5% or less.